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ENDANGERED SPECIES 373 special need for biological surveys to determine the status of rare fishes and gain legal protection for those near extinction, particularly in Mexico and, to a lesser extent, Canada. Williams et aI. (1989) stressed the need for long-term monitoring programs to provide baseline data on the status of rare fishes and allow future assessment of both fish populations and their habitats. Managers of rare fishes must proceed cautiously, howev1er, because tbe field is relatively new and much remains to be learned (Meffe 1986). We must, for example, avoid over-monitoring populations of threatened or endangered fisbes~ it is possible to study some species to extinction. Because of political and biological urgency regarding recovery, aspects of basic biology (e.g., genetics, reproduction, growth, age structure, sex ratio) have often been neglected in research on rare fishes. Many suggestions of MIot (1989) and Soule and Kohm (1989) regarding research directions for conservation biology should be applied to rare fishes; emphasis on ecosystem fragmentation, biology of small systems, reproduction, reintroduction, and effects of stress and disease is justified. Population dynamics and habitat needs, with particular emphasis on early life stages, must be understood for effective management. Single-sp'~cies approaches to recovery efforts must and have begun to give way to considering endangered fishes as components of complex ecosystems. Biologists must also recognize their obligations as informed citizens to see that laws that protf~ct species or tbeir habitats are passed, modified as necessary, and enforced. 15.5.1 Managing Fish and Habitat Specific practices that can be applied to management of endangered fishes include (I) maintaining and enhancing historic populations; (2) protecting, ex- panding, or restoring habitat; (3) moving specimens to refuges; (4) rearing and stocking in new or formerly occupied areas; (5) minimizing introductions and undesirable effects of introduced nonnative organisms; and (6) controlling exploi- tation. First, factors leading to species rarity must be identified and, if possible, controlled. We have listed maintaining and enhancing historic native populations first as a reminder of their importance. This could involve some or all of the other management practices considered in this section. One approach to avoiding extinction. however, might be to simply leave some populations and their habitats alone. Saving entire species from extinction is of paramount importance. Habitat should be a primary consideration in recovery of rare fishes. Land acquisition as accomplished in the Death Valley drainage is the most effective means of protecting habitat for e:ndangered species. Other approaches involve participation in pollution-control efforts. land-use planning, and legal actions to prevent habitat destruction. Definition and development of optimal habitats is far more effective in enhancing endangered fish populations than imposition of restrictive regulations (Deacon et aI. 1979). Johnson and Rinne (1982) noted that protection and enhancement of habitats is the almost universal goal of fish recovery plans, but recovery teams have generally left implementation to the discretion of land managers. They suggested that existing habitats be protected through increased federal management, prioritizing protected habitats, and use of ecosystem-based recovery teams. To make protection more efficient, only optimal p...-